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We recently observed and described two patients with unilateral periflexural exanthema (UPE). This occurred in a 24-year-old woman after she received the COVID-19 vaccine and in a one-year-old female baby affected by COVID-19.

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This concurrent observation is very interesting as the same cutaneous eruption was detected in patients who have in common a potential immune response against Spike protein of the virus.

UPE has the same clinical presentation as asymmetric periflexural exanthema of childhood (APEC), which is an unusual eruption in children, which is thought to be secondary to herpesvirus-6 infection.

The unilaterality of the rash may be explained by a different immunogenicity of keratinocytes of one side of the body, maybe secondary to a post-zygotic mutation. UPE and APEC are usually asymptomatic or mildly itchy and spontaneously remit within weeks.

It was worth noting to report these novel findings in patients with COVID-19 or after COVID-19 vaccine to make clinicians aware of these possible rare and uncommon eruptions.

– Dr Vincenzo Piccolo

Full paper:

Sechi A, Bassi A, Mazzatenta C, Cutrone M, Naldi L, Argenziano G, Piccolo V. Covid-19 and Covid-19 vaccine can slide along sides: a report of two cases of unilateral periflexural exanthema. J Eur Acad Dermatol Venereol. 2022 Mar 19. doi: 10.1111/jdv.18093.

Watch Dr Vincenzo Piccolo’s recent video review on this topic.

Read more recent research from Dr Vincenzo Piccolo: Topical ivermectin for neonatal scabies